Two Very Rare Cases of Metastatic Thymic Carcinoma with Sjogren's Syndrome: A Case Series

Abstract

Thymic tumours are rare thoracic malignancies with thymic carcinoma accounting for approximately 12% of all thymic tumours compared to thymomas which account for approximately 86%. Unlike thymomas, it is very rare for thymic carcinomas to be associated with autoimmune disorders or paraneoplastic syndromes. When these phenomena do occur, the vast majority are myasthenia gravis, pure red cell aplasia, or systemic lupus erythematous. Paraneoplastic Sjogren's syndrome is a rare complication of thymic carcinoma, with only two cases previously reported. Here we present 2 cases of patients with metastatic thymic carcinoma who developed autoimmune phenomena consistent with Sjogren's syndrome without classical symptoms prior to treatment. One patient opted for surveillance of their malignancy, while the other underwent chemoimmunotherapy with favourable results. These case reports describe two distinctive clinical presentations of a rare paraneoplastic phenomenon.

Keywords: Autoimmune disorder; Immunotherapy; Paraneoplastic syndrome; Sjogren’s syndrome; Thymic carcinoma.

Fig. 1.

Imaging series of thymic carcinoma, pericardial effusion, and pleural effusions. a Axial PET CT showing anterior mediastinal mass and right pleural disease. b Axial CT upper abdomen showing 15.4 mm pericardial effusion. c Axial CT upper abdomen showing bilateral pleural effusions.

Fig. 2.

Morphological and immunohistochemical features of thymic carcinoma and pericarditis. a Haematoxylin and eosin stain – high-grade carcinoma with solid sheets. b Immunohistochemical staining for PAX8. c Immunohistochemical staining for CD5. d Immunohistochemical staining for CD117. e Dual immunohistochemical staining for p40 (brown chromogen) and CK5/6 (red chromogen). f Haematoxylin and eosin stain of the pericardial biopsy – acute inflammation with fibrinoid material and granulation tissue. Figure panels a–e magnification, ×20, panel f magnification, ×10.

Fig. 3.

Image series of metastatic thymic carcinoma. a Coronal PET CT showing thymic carcinoma with liver lesions. b Chest X-ray showing thymic mass. c Axial CT upper abdomen showing liver metastases.

Fig. 4.

Morphological and immunohistochemical features of thymic carcinoma. a Tumour nests with abundant necrosis, with similar morphology to the tumour in case 1 (Fig. 2). b Immunohistochemical staining for PAX8. c Immunohistochemical staining for CD5. d Immunohistochemical staining for CD117. e Immunohistochemistry for cytokeratin. f Dual immunohistochemical staining for p40 (brown chromogen) and CK5/6 (red chromogen). a–f magnification, ×20.